1. Field of the Invention
The present invention relates generally to a communication network designing circuit, a designing method thereof, a storage medium storing its control program and a transmission medium. More particularly, the present invention relates to a designing method of a communication service between multiple points for permitting arbitrary communication within a given range by providing a traffic amount of data in-flowing from an ingress node through which data enters from other network and a traffic amount of data flowing out from an egress node through which data is fed to other network, in an objective network consisted of a plurality of nodes and connected to other networks.
2. Description of the Related Art
Conventionally, in a communication network designing method, such as a method disclosed in “Restoration strategies and spare capacity requirements in self-healing ATM networks” (Yijun Xiong and Lorne Mason, INFOCOM'97, April, 1997), a path for communication between single nodes has been designed. In the disclosed methods, a communication amount is determined for each node pair to communicate and a path of fixed band is set between each node pair.
One example of a result of design based on the conventional designing method is shown in FIG. 4. At first, the conventional designing method will be discussed with reference to FIG. 4. In FIG. 4, the references sign d1 denotes a network range to be objective for the designing method, which will be referred to as objective network. The reference signs n1 to n6 identify nodes, and u1 to u4 identify networks other than design objective range. Communication traffic between these networks flows in and out the objective network. Hereinafter, the networks other than object will be referred to as user network.
For example, u1 to u4 denote different stations of the user network. Among nodes, a node located on a boundary between the objective network and the user network will be referred to as edge node. Nodes located in the objective network will be referred to as core nodes.
When data enters from the user network, the edge node is taken as an ingress node, and when data flow to the user network, the edge node is taken as an egress node. Normally, the edge node serves both for the ingress node and the egress node. It should be noted that the node generally referred to includes both of the edge node and the core node. On the other hand, lines between nodes and between the node and the network out of object represent links. These links are expressed, such as (n1, n2), (u1, n2) and so forth.
In FIG. 4, only one link is described, it represents presence of links in both directions. For example, a link (n1, n2) includes both of a link from n1 to n2 and a link from n2 to n1. It should be noted that, between one node pair, any number of links may be present. The link has a band in attribute. In FIG. 4, only bands of the portions necessary for discussion are described.
Now, in a certain communication service between multiple points, it is assumed that data flows in through an ingress node n3 at a data rate of 2 Mb/s, data flows in through an ingress node n1 at a data rate of 1 Mb/s, data flows out through an egress node n6 at a data rate of 2 Mb/s, and data flows out through an egress node n5 at a data rate of 1 Mb/s.
In the conventional designing method, fixed paths have to be set between respective ingress nodes and egress nodes. For example, paths are designed by determining each traffic amout that <n3,n6> us 1 Mb/s, <n1,n5> is 2 Mb/s, <n1,n6> is 1 Mb/s, <n1,n5> is 1 Mb/s. Here, paths are expressed by p1 to p4. An example where paths as shown in FIG. 4 are designed by the conventional design method, is shown.
However, in the conventional design method, since each path is designed by providing communication amount per ingress/egress pair, it become not possible to design a service in a mode permitting arbitrary communication within a given range of communication amount by providing the communication amount entering into each start node from the user network and the communication amount exiting from each end node to the user network.